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Designation: D4753 − 07

Standard Guide for

Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing1 This standard is issued under the fixed designation D4753; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. Scope*

to comply with standard metric practice. In addition, the term “standard mass(es)” is used instead of standard “standard weight(s)” when referring to a piece of material of known specified mass used to compare or measure the mass of other masses.

1.1 This guide provides minimum requirements for generalpurpose scales, balances, and standard masses used in testing soil, rock, and related construction materials.

1.8 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgement. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged nor should this document be applied without consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.

1.2 This guide provides guidance for evaluating, selecting, and specifying general purpose scales, balances, and standard masses used in testing soil, rock, and related construction materials. 1.3 The accuracy requirements for balances and scales are specified in terms of the combined effect of all sources of error contributing to overall balance performance. The measurement of specific sources of error and consideration of details pertaining to balance construction have been intentionally avoided. 1.4 This guide does not include requirements for balances and scales having accuracies greater than those generally required in testing soil, rock, and related construction materials or for research programs or specialized testing requirements.

2. Referenced Documents 2.1 ASTM Standards:2 D653 Terminology Relating to Soil, Rock, and Contained Fluids E617 Specification for Laboratory Weights and Precision Mass Standards 2.2 National Institute of Standards and Technology Documents: NIST Handbook 44 Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices3 2.3 International Organization for Legal Metrology (OIML): International Recommendation No. 20 Weights of Accuracy Classes E1, E2, F1, F2, M1 from 50 kg to 1 mg4 International Recommendation No. 34

1.5 This guide does not apply to nongraduated balances. 1.6 This guide does not address the methods used to verify or quantify specific parameters dealing with balances and scales. For a description of tests used in evaluating balance performance, see NIST Handbook 44. 1.7 This guide is not intended to be used as a specification for the purchase of balances and scales. NOTE 1—The National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards (NBS), and the International Organization of Legal Metrology (OIML) publish standards or practices that specify construction requirements as well as performance guides for balances. ASTM, OIML, and NIST publish construction standards and tolerances for standard masses. NOTE 2—The terms “mass” and “determine the mass of” are used in this standard instead of the more commonly used terms “weight” and “weigh”

2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [email protected]. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 3 Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov. 4 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:// www.access.gpo.gov.

1 This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.91 on Standards Development and Review. Current edition approved July 15, 2007. Published August 2007. Originally approved in 1987. Last previous edition approved in 2002 as D4753 – 02. DOI: 10.1520/D4753-07.

*A Summary of Changes section appears at the end of this standard Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

Copyright by ASTM Int'l (all rights reserved);

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D4753 − 07 3.2.11.1 Discussion—Linearity implies that the deviation from the true values are a continuous function of the applied mass. Thus, obtaining enough values of the true applied mass versus balance reading to establish a relation between applied mass and output should give the error that will occur at any applied mass. Linearity, then, is a statement about the systematic (nonrandom) error of a balance. Superimposed on the linearity are precision and other effects, such as off-center errors, temperature effects, etc. Linearity is a measure of balance performance over its full range, and on most balances adjustments can be made to alter the useableness of a balance with a given linearity for measurements within a particular range of use. 3.2.12 nongraduated balance—balances not fitted with a scale numbered in units of mass. 3.2.13 off-center error—of a top loading or platform balance, the difference in indicated value when a mass is shifted to various positions on the loading area (pan or platform); eccentric load error. 3.2.13.1 Discussion—The test for off-center error is called the shift test, or offcenter-load test. Information about balance performance under eccentric loadings is not normally found in product literature but such information can usually be obtained by contacting the manufacturer directly. 3.2.14 precision of a balance—the degree of agreement between the indications of a balance for repeated determinations of mass of the same mass under essentially the same conditions. It is usually expressed quantitatively as a standard deviation of a series of mass determinations, or as a function of the range of several mass determinations. See repeatability type II, reproducibility. 3.2.15 readability type I—the value of the smallest unit of mass that can be read without estimation over the given range of measurement either directly or by use of a vernier or micrometer. 3.2.16 readability type II—the value of the smallest unit of mass that can be read with estimation over the given range of measurement. 3.2.17 readability type III—the value of the smallest unit of mass that can be read when in-service conditions such as draft, vibration, and other environmental conditions affect the balance while the balance is in use, but not smaller than readability Type I. 3.2.18 repeatability type I—the degree of agreement between the indications of a balance for repeated determinations of the same mass under essentially the same conditions. The degree of agreement (qualitatively). 3.2.19 repeatability type II—see precision of a balance. 3.2.20 reproducibility—see precision of a balance. 3.2.21 scale—see balance. 3.2.22 sensitivity—the ratio of the deflection (DL) of the balance indicator or self-indicating display to the mass (DM) causing the deflection; S = DL/DM at a given mass.

3. Terminology 3.1 Definitions—For definitions of terms used in this guide refer to Terminology D653. 3.2 Definitions of Terms Specific to This Standard: 3.2.1 accurate—a balance is “accurate” when its performance (its indication as determined by tests made with suitable standards) conforms to the standard within the applicable tolerances and other performance requirements. Balances that fail to conform are “inaccurate.” 3.2.2 balance—an instrument for determining the mass of an object by the action of gravity on the object. See scale. 3.2.2.1 Discussion—In this guide and in common usage, the terms balance and scale are used interchangeably. The term balance is more often used in scientific fields of application. The term scale usually refers to instruments intended for commercial or industrial applications, and when so used, usually implies an instrument of lesser performance than a balance. 3.2.3 basic condition—a condition that must be met before a basic measurement for evaluating a balance can be performed. 3.2.4 basic measurement (of error)—a basic measurement for evaluating a balance is performed by (1) determining the change of indication of the balance when a known mass is added to or subtracted from any mass already on the balance; and (2 ) taking the difference between the change in the indication determined and the known value of the mass. 3.2.5 basic tolerance—tolerances that are established by a particular code for a particular device under all normal tests, whether maintenance or acceptance. Basic tolerances include minimum tolerance values when these are specified. Special tolerances, identified as such and pertaining to special tests, are not basic tolerances. 3.2.6 capacity—of a balance , the maximum mass recommended by the manufacturer, disregarding any additional capability supplied by a taring device. 3.2.7 general-purpose balance—any balance used to make a general purpose determination of mass. See general-purpose determination of mass. 3.2.8 general-purpose determination of mass— a single determination of mass using a balance (not a special purpose determination of mass involving repeat determinations of mass, averages, standard deviations, corrections, etc.). 3.2.9 general-purpose standard mass—a standard mass used with a balance to make a general purpose determination of mass. See general-purpose determination of mass. 3.2.10 hysteresis—the difference between successive measurements of a standard mass when the standard mass is measured after a cycle of adding, and then removing (or removing, then adding) mass from the balance. 3.2.11 linearity error—plus or minus deviation from the theoretically straight-lined (linear) course of two interdependent values. In balances, this expression is applied to the plus or minus deviation of the indicated measurement value from the true (actual) value of the mass. Copyright by ASTM Int'l (all rights reserved);

NOTE 3—Values for sensitivity are sometimes seen expressed in terms of mass units. When used in this way in reference to a nonself-indicating balance, sensitivity refers to the reciprocal of sensitivity or the change in

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D4753 − 07 maintenance tolerances given in Specification E617 for Class 6 standard masses are to be considered acceptance tolerances for purposes of this guide and the maintenance tolerances twice those values. The tolerances values given in Table 2 correspond to the minimum acceptable maintenance tolerances under this guide.

mass required to change the position of equilibrium (rest point) a specified amount, usually one division on the balance indicator. When used in reference to self-indicating balances, it refers to the change in mass required to change the indication by one scale division.

3.2.23 standard mass—an object of specified mass and construction used with balances, and for the verification of balances and other masses. 3.2.24 taring range—a range within which it is possible to reset the indicator or display to zero by use of the tare device. 3.2.25 tolerance—a value fixing the limit of allowable error or departure from true performance or value.

NOTE 5—Former NIST Class J, M, S, S-1, P, and Q standard masses meet this guide, as do OIML Class M1 standard masses (IR No. 20).

7. Evaluation of General-Purpose Balances 7.1 Basic Tolerance—Table 1 shows the basic tolerances for all classes of general-purpose balances used in soil or rock testing that are covered by this guide. The basic tolerances shown apply to basic measurements made when evaluating a balance. 7.1.1 A basic measurement for evaluating a balance is performed by determining the change of indication of the balance when a known mass is added to or subtracted from any mass already on the balance, and then taking the difference between the change in the indication determined and the known value of the mass. To evaluate a balance, the basic tolerances shown in Table 1 are applied to the known value of the mass used in the basic measurement. The result of a basic measurement must fall within the error allowed by the basic tolerance.

NOTE 4—For additional terms used in this guide related to balances and standard masses, see NIST Handbook 44 or OIML IR No. 3.

4. Significance and Use 4.1 This guide provides those using standards related to soil, rock, and related construction materials, with a means for selecting the balance required for a particular standard. 4.2 This guide provides those writing standards pertaining to soil, rock, and related construction materials with a means for specifying the balance capabilities required for a particular standard and for describing the balance selected in a uniform fashion. 4.3 This guide provides agencies conducting soil, rock, and related construction materials, testing with guidance for selecting and evaluating general purpose balances and standard masses.

NOTE 6—For nearly all determinations of mass encountered in soils testing, the value of interest is the difference between two determinations of mass. In cases where the difference between the two determinations of mass is small, relative to the total masses determined, it is desirable to specify a tolerance based on the difference between the two determinations of mass to relieve what might otherwise be an excessively stringent tolerance. NOTE 7—A no load condition may be treated as a mass of 0.0 g and may be considered a mass on the balance.

4.4 This guide provides inspection organizations with criteria for evaluating general purpose balances and standard masses. 5. Requirements for General-Purpose Balances 5.1 General-purpose balances shall be judged accurate for a given class if their indications meet the basic tolerances shown in Table 1.

TABLE 2 Maintenance Tolerances for General-Purpose Standard Masses

6. Requirements for General-Purpose Masses 6.1 General-purpose standard masses for use in verification balances and testing of soil and rock shall conform to the requirements in Specification E617 for Type I or Type II, Grade S, O, or P standard masses and have tolerance limits equal to or better than those for Class 6 standard masses except that the

Denomination 20 kg 10 kg 5 kg 3 kg 2 kg 1 kg 500 g 300 g 200 g 100 g 50 g 30 g 20 g 10 g 5g 3g 2g 1g 500 mg 300 mg 200 mg 100 mg

TABLE 1 Requirements for General-Purpose Balances Class

Test Mass,A g

GP1

$20